VR360 Hemispherical to Equirectangular¶

Description

This effect/filter converts a video frame with two hemispherical images to a single equirectangular frame.

The plugin assumes that both hemispheres are in the frame. If you have a camera like the Garmin Virb360 that produces two videos, one from each camera, you should start by converting them to a single movie by placing them side by side using, for example, ffmpeg (you can also add parameters to produce lossless, intra-only output here for easier editing):

ffmpeg \
 -i left.mp4 \
 -i right.mp4 \
 -filter_complex hstack \
 output.mp4

Parameters

Parameter	Value	Description
Projection	Selection	The fisheye projection type. Currently only equidistant fisheyes, like the Ricoh Theta and Garmin Virb360 are supported.
Use sensor response parameters	Switch	Switch on to use sensor response parameters (see EMoR h(x) parameters below)
Interpolation	Selection	Determines the sampling method
Alignment Yaw / Pitch / Roll	Integer	Adjust the rotation along the Z- (yaw), X- (pitch) and Y-axis (roll) to compensate for any alignment differences
Lens FOV	Integer	Field of View of a single hemisphere in degrees
Lens Radius	Float	Radius of the image circle as a fraction of the frame width (for example 0.25 = 25% of 1920)
Front X / Y	Float	Defines the center of the image of the front-facing camera. X is expressed as a fraction of the image width, Y as a fraction of the image height.
Front UP	Integer	Defines the „up“ direction in the image in degrees counting clockwise from a directions towards the top edge
Back X / Y	Float	Defines the center of the image of the back-facing camera. X is expressed as a fraction of the image width, Y as a fraction of the image height.
Back UP	Integer	Defines the „up“ direction in the image in degrees counting clockwise from a directions towards the top edge
Nadir Radius / Start	Float	Adjust the nadir of the camera if you have parts of the camera or equipment in the image
Lens distortion A / B / C	Float	Lens distortion correction parameters. The first three parameters are the same as in Hugin.
Lens distortion radius	Float	Lens distortion correction parameters. If you use Hugin parameters, the Radius should be set to the value of (0.5 * min(image width, image height) / image width). For a 2:1 aspect dual hemispherical image, that would be 0.25.
Lens vignetting A / B / C / D	Float	Lens vignetting correction parameters. The first four parameters are the same as in Hugin, corresponding to the V_a , V_b , V_c , and V_d image parameters.
Lens vignetting radius	Float	If you use Hugin parameters, the radius should be set to the value of (0.5 * image diagonal / image width). For a 2:1 aspect dual hemispherical image, that would be 0.5590. Use the `A` parameter to scale the effect and avoid overexposing highlights.
EMoR h(1 / 2 / 3 / 4 / 5)	Float	Sensor response parameters. The EMoR h(x) parameters are the same as Hugin‘s R_a - R_e in the lens parameters. If you use Hugin-derived values for vignetting correction, you should also use these parameters, as Hugin‘s vignetting correction assumes that the sensor response has been corrected.

The following selection items are available:

Projection

Equidistant Fisheye

default

Interpolation

Nearest-Neighbor	default
Bilinear